Method and apparatus for conveying and heat treating glass sheets over a gas support bed



Aug. 27. 1968 MOMASTER ETAL 3,399,042

METHOD AND APPARATUS FOR CONVEYING AND HEAT TREATING GLASS SHEETS OVER AGAS SUPPORT BED Original Filed Nov. 29, 1963 2 Sheets-Sheet 1 INVENTORSAug. 27, 1968 MOMASTER ET AL 3,399,042

METHOD AND APPARATUS FOR CONVEYING AND HEAT TREATING GLASS SHEETS OVER AGAS SUPPORT BED Original Filed Nov. 29, 1963 2 Sheets-Sheet 2 INVENTORYZ?" a M06? R/VEKI United States Patent 3,399 042 METHOD AND APPARATUSFOR CONVEYING AND HEAT TREATING GLASS SHEETS OVER A GAS SUPPORT BEDHarold A. McMaster, Woodville, and Norman C.

Nitschke, Perrysburg, Ohio, assignors to Permaglass, Inc., Woodville,Ohio, a corporation of Ohio Original application Nov. 29, 1963, Ser. No.326,713, now Patent No. 3,332,759, dated July 25, 1967. Divided and thisapplication Sept. 15, 1966, Ser. No. 579,629

11 Claims. (Cl. 65-25) ABSTRACT OF THE DISCLOSURE This application is adivision of application Ser. No. 326,713, filed Nov. 29, 1963, nowPatent 3,332,759 in the names of Harold A. McMaster and Norman C.Nitschke and assigned to the assignee of the instant invention.

It is a principal object of the present invention to provide an improvedmethod and apparatus for manufacturing sheets of glass or the likeefliciently and at relatively low cost. More specifically, it is anobject of the invention to provide a glass manufacturing apparatus ofthe type described whereby tempered curved glass sheets of exceptionallyhigh quality can be manufactured on a continuous high production basisat relatively low cost with very low scrap or breakage losses. Thesealong with other objects, features and advantages of the invention willappear more clearly from the following detailed description of apreferred embodiment thereof made with reference to the drawings inwhich:

FIGURE 1 is an isometric view, with parts broken away and partiallyschematic, of the preferred apparatus and illustrates the bedconfiguration into and through the heating furnace wherein the glasssheets are curved, and into and through the blasthead wherein the curvedglass sheets are tempered;

FIGURE 2 is a cross sectional view of a portion of the conveyor meansextending along one side of the furnace of FIGURE 1 illustrating theposition of the various parts;

FIGURE 3 is a plan view of the conveyor system and conveyor support foottaken substantially along the line 33 of FIGURE 2 and looking in thedirection of the arrows;

FIGURE 4 is a partial elevational view of a portion of the conveyorchain of FIGURES 2 and 3;

FIGURE 5 is a schematic view of a portion of the bed assembly andconveyor means showing the position of the glass sheets fortransportation across the bed;

FIGURE 6 is a perspective view of a glass sheet such as might be treatedin the furnace illustrated in FIGURE 1 and wherein the axis of thecurvature is parallel to the edge of the sheet;

FIGURE 7 is a schematic view of a portion of the bed assembly showingglass sheets in another portion for transportation across the bed andthrough the furnace of FIGURE 1;

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FIGURE 8 is a perspective view of a glass sheet such as might be treatedin the furnace of FIGURE 1 and with the axis of curvature angularlydisposed relative to the edge of the glass sheet.

Referring more particularly to FIGURE 1, the apparatus shown comprisesan elongate perforated bed, illustrated generally by the numeral 20which, in the actual embodiment herein shown, is about feet long and iscomposed of three main sections. These sections include a loadingsection 21, a heating and bending section 22, and a tempering section23. The heating and bending section 22 is within and constitutes thefloor of an elongate furnace structure, illustrated generally by thenumeral 24, and the tempering section 23 extends through a cooling blasthead, illustrated generally by the numeral 25. The bed is flatthroughout section 21 and most of section 22; and approximatelytwo-thirds of the way through section 22 gradually becomes curved in adirection transverse to the longitudinal axis of the bed. Bed section 23within the blasthead 25 and the portion of section 22 toward the end ofthe furnace adjacent the blasthead have a uniform transverse curvaturesubstantially the same as that desired of the glass sheets to bemanufactured. The plane of the bed is tilted about the longitudinal axisthereof at a slight angle to the horizontal, preferably from about 3 to12, and hence the left longitudinal edge of the bed, as shown at 26, islower than the right edge 27. A chain conveyor system, illustratedgenerally by the numeral 28, carrying spaced pairs of glass sheetsupport pads 29, serves to move the glass sheets over the bed 20 fromthe loading section 21 through the furnace 24 and through the blasthead25. Gas emitted from perforations in the bed 20 provides a film orcushion of gas on the bed for flotation of the glass sheets thereover ina manner to be described in detail hereinafter. In essence, then, andwithout attention at this time to important features and details, theapparatus operates as follows: The glass sheets 30 to be curved andtempered are placed onto the bed at loading section 21 with the bottomedge of each sheet resting on a pair of pads 29 secured to the conveyorchain 28. The glass sheets are conveyed by the chain and float over thebed out of contact therewith by reason of the gas emitted from theperforations in the bed. The floating glass sheets are thus guidedthrough the furnace 24 where they are heated to deformation temperatureby the hot gases emitted from the bed perforations and as they reach thecurved porion of section 22, the sheets sag under gravity to conform tothe curvature thereof, all the while supported on gas out of contactwith the bed. Hence, when the sheets reach the end of the furnace, theyare shaped with the full curvature desired. Transportation of thefloating heated curved glass sheets then continues through the blasthead25 where they are tempered by the cooling air projected from the bedperforations in the blasthead.

The bed comprises a plurality of blocks 31 which are aligned and inabutting relationship. The bed has a flat upper surface over most of itslength'in order to provide suificient time for the sheets to be heatedto deformation temperature as they are moved along the bed. In a zonetoward the end of the furnace, the bed surface contour changes graduallyfrom flat to curved. At the end of the furnace and into the blasthead,the contour of the bed 20 is of a constant degree of transversecurvature to provide the curvature desired in the glass sheets.

Conveyor system As has been previously pointed out, the support bed 20,extending through the furnace 24 and through the blasthead 25, isdisposed therewith at a slight angle, 12 in the embodiment shown,relative to the horizontal plane of the furnace. With the glass sheet-30floating on a blanket of gases above the support bed 20 and the blanketof gases being of substantially constant thickness, it is obvious thatthe glass sheet will have a component of weight force. directed alongthe plane of the surface of the support bed 20. Due to this angularityand this component of force, it is possible to provide a conveyor systemwhich will transport the glass sheets along the length of the supportbed with very light contact with the glass sheet 30. It will be furtherapparent that with the glass sheet 30 floating on the blanket of hotgases over the support bed 20, that very little force will be necessaryto transport or convey the glass sheet along the bed, and thus verylight contact in the direction of travel is all that is necessary.

Referring now to FIGURES 1 through 8, the conveyor system for the glasssheets includes a guide rail 101 which is formed in aligned sections andextends alongside the lower edge of the bed for the entire length of theloading station, the furnace, and blasthead. The rail 101 may besuitably supported by posts 102, supported on the furnace superstructurein a suitable manner. Riding on guide rail 101 is a conveyor chain,indicated generally by the numeral 103, of typical link and bearing rodconstruction having spaced members 104 depending downwardly therefrom atspaced points therealong and straddling the rail 101. An electric motordriven sprocket serves as means for driving the chain. The particularfeatures of the chain and its drive means whereby the chain ismaintained taut and is driven at a smooth uniform speed through thefurnace and blasthead are described in detail and claimed in UnitedStates Patent application Ser. No. 478,521 filed July 15, 1965, nowPatent No. 3,282,447 in the name of Harold A. McMaster and assigned tothe assignee of the present invention.

Extending inwardly from the chain 103 toward the support bed 20, and atproperly spaced intervals therealong, are support members or feet,indicated generally by the numeral 105. Each support foot 105 includes alower plate member 106 which is supported on the support bed 20 byflotation in the same manner as the glass sheets 30. Thus, the supportmembers 105 are at least partially supported by gas out of contact withthe upper surface of the bed. The instant invention, therefore, setforth a novel method including the steps of contacting at least one edgeof the sheet of glass with the support member 105 and supporting atleast a portion of the support member 105 on gas and thereafter movingthe support member 105 to impart movement to the glass sheet. The platemembers are provided with upstanding ribs 107 to which are securedsuitable rods 108 extending and secured to the conveyor chain 103. Theconnection 109 between the rods 108 and the ribs 107 is rather loose toallow some pivotal movement for purposes to be hereinafter described.The conveyor means thus includes all of the components necessary to theconveyor assembly such as the supports 102, the rail 101, the powerinput to move the chain 103, etc. However, the conveyor means doesinclude a drive means which, as illustrated, includes the rod 108 and/orthe chain 103. Thus, the pins 109 are means connecting the supports 105to the drive means in a manner to permit relative movement of thesupport 105 with respect to the drive means in a direction generallytransverse the longitudinal axis of the bed and, more specifically,pivotally connects the support members 105 to the drive means to allowpivotal movement therebetween in a plane generally transverse thelongitudinal axis of the bed.

Extending upwardly from the inner edge of lower plate 106 issubstantially vertical plate member 110 provided with a series ofvertical lands and grooves 111 and 112, respectively. It is desirablethat the face of plate member 110 be as perpendicular as possible to theplane of the glass sheet 30 disposed thereagainst, and the glass sheet30 with its component of weight force in the direction of its surface,lightly engages the lands 111 on the upstanding plates'110. The slightfrictional engagement of theplate members 110 with the glass sheets 30is sufficient to convey the glass sheets through the furnace 24 andblasthead 25 along with the chain 103. Extending outwardly from thetopedge of the plate members 110 may be spaced tabs 113 which serve as astop means to prevent extreme upward movement of the glass sheets 30.Normally, however, the glass sheets do not engage the tabs 113 but areengaged with the upstanding plates 110 toward the lower edge thereof.

Extending outwardly from the rod members 108are plates 114 which aresecured to the rod members 108 and to the chain 103 to properlydirectthe rod members 1% toward the interior of the furnace 24. Such plates114 maintain the precise angularity of the rod members relative to thechain 102 that is desirable in the installation. The plate'members 114also serve to structurally maintain the rod members on the chain 103.

As indicated in FIGURE 5, the support feet engage the glass sheets 30,one at the forward end of the sheet and the other at the rearward end ofthe sheet. If more support is necessary for the glass sheets 30, or ifthe glass sheets 30 are of extreme length, it may be desirable toprovide additional support feet 104, located as necessary for support ofthe glass.

As illustrated in FIGURES 5 and 6, the glass sheets supported by thefeet 105 come out of the furnace 24 and blasthead 25 with a curvatureabout the longitudinal axis of the glass sheets 30. This is accomplishedby spacing the front support foot the same distance from the chain 103as the rear support foot, thus having the edge of the glass sheet 30parallel to its longitudinal center line. However, if it is desired toform glass sheets with a cylindrical curvature about an axis at an angleto the edge of the glass, this can be conveniently accomplished with theapparatus-of this invention, as is illustrated in FIGURES 7 and 8. Asshown in these figures, the glass sheet has a curvature about a centerline angularly disposed relative to the central axis of the glass sheet.This is accomplished by having the distance of the front support foot105 from the chain 103 greater than is the distance of the rear supportfoot, as illustrated in FIGURE 7. Under such conditions, the glass sheet30 will be forced to float along the support bed 20 obliquely of thelongitudinal axis of the support bed, and thus the desired curvature andaxis of curvature are obtained. Where considerable angularity betweenthe axis of curvature and the longitudinal axis of the sheet is desired,it may be advantageous to provide an extension on the rear foot toengage the rear edge of the glass and thereby insure against the glasssheet slipping :from the support feet within the furnace. It will beapparent that any axis of curvature may be provided by the combinationof support foot location and the surface contourof the support bed 20.The instant invention, therefore, discloses a method of curving a sheetof glass 30 as illustrated in FIGURE 7 about an axis (i.e., thecenterline of the bed illustrated in FIGURE 7) which is in intersectingrelation toan edge of the sheet, that edge being the edge next adjacentthe longitudinal edge of the bed which in turn is adjacent the chain103. The method includes the step of placing the sheet of glass 30 ongas above the elongated bed which has a transversely curved portion in amanner to place the edge in an oriented position adjacent thelongitudinally extending edge of the bed adjacentthe conveyor and withthe edge at an angle in intersecting relationship to the longitudinallyextending edge of the bed, as illustrated in FIGURE 7. The sheet isvthenheated to deformation temperature and moved along the bed while the edgeis maintained in the oriented position as illustrated in FIGURE 7. Thenovel method may also be expressed as including the step of contactingan edge of the sheet and conveying the sheet along the bed ina mannerthat the edge which is contacted is on a line in intersecting relationto the edge of the bed.

The conveyor can be of constant speed or it can be of variable speed sothat the glass sheets can be moved relatively rapidly into the blastheadand then slowed down within the blasthead. Of course, where a singlevariable speed chain is used this will mean that the sheets within thefurnace also move at varying speeds. In one method of operation, theglass sheets are sent through the apparatus in spaced pairs, theconveyor speed changes being sequenced such that as a pair of sheets isbeing moved into the blasthead at slightly increased speed, spaced pairsof sheets within the furnace are fore and aft of but not directly overthe curvature transition zone. Of course, other arrangements can be usedif desired. For example, a separate higher speed conveyor chain can beused for the blasthead, such chain being cooperative with that throughthe furnace so that the glass sheets are transferred from the one to theother at the end of the furnace. Where this system is used it isdesirable that means he provided to preheat the support feet on theblasthead chain before they come in contact with the hot glass lestchill cracks develop in the sheets when contacted by such support feet.

To inhibit the flow of cool air into the furnace from the blasthead andhot gas into the blasthead from the furnace, a reciproeable door can beprovided between the furnace and blasthead as indicated in brokenoutline at 119 in FIGURE 1. Such door can be raised to allow passage ofone or more glass sheets into the blasthead, and then lowered again bysuitable means cooperative with the chain or the chain drive means.

The invention has been described in an illustrative manner and it is tobe understood that the terminology which has been used is intended to bein the nature of words of description rather than of limitation.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. Apparatus for treating sheets of glass comprising an elongated bedhaving passages therein, conveyor means for moving the sheets of glassover said bed, and means for causing gas to be emitted from saidpassages to support the glass sheet above the bed, said conveyor meansincluding drive means movable longitudinally of said bed and spacedglass sheet supports extending transversely over the longitudinallyextending edge of said bed to contact the edges of said sheets andimpart movement thereto longitudinally along the bed, and meansconnecting said supports to said drive means for permitting freemovement of said supports relative to said drive means in a directiongenerally transverse to the longitudinal axis of said bed.

2. An apparatus as set forth in claim 1 wherein said means connectingsaid supports and said drive means comprises a pivot means to allowpivotal movement of said supports relative to said drive means in aplane generally transverse to the longitudinal axis of the bed.

3. Apparatus as set forth in claim 1 wherein said supports are arrangedin spaced pairs which extend over a longitudinally extending edge of thebed, each pair for supporting a separate sheet of glass, and wherein onesupport of each pair extends further toward the center of the bed thanthe other support of said pair whereby a glass sheet conveyed by saidpair of supports is positioned with the edge thereof which is adjacentsaid edge of the bed at an angle to the longitudinal axis of the bed.

4. The apparatus set forth in claim 1 wherein each of said supportsincludes a plate member overlying some of the passages in said bed and asecond member angularly disposed to said plate member for contacting theedge of the glass sheet on said support.

5. The apparatus set forth in claim 4 wherein said second member isprovided with spaced raised portions for contacting the edge of theglass sheet.

6. The apparatus set forth in claim 1 wherein said drive means comprisesa member extending in an endless loop.

7. The apparatus set forth in claim 1 wherein said supports are providedwith means for preventing the glass sheets in contact therewith frombeing floated off of said supports by the gas.

8 Apparatus for conveying a sheet comprising an elongated bed havingpassages therein, conveyor means for moving the sheet over said bed, andmeans for causing gas to be emitted from said passages to support theglass sheet above said bed, said conveyor means including a memberextending transversely over the longitudinally extending edge of saidbed to contact the edges of said sheet and impart movement theretolongitudinally along the bed, and means connecting said members to saidconveyor for permitting free movement of said members relative to saidconveyor in a direction transverse to the longitudinal axis of said bed,said member being at least partially supported by said gas over saidbed.

9. A method of curving a sheet of glass about an axis which is inintersecting relation to an edge of said sheet comprising: supportingsaid sheet on gas above an elongated bed which has a transversely curvedportion and orienting said edge in a position adjacent a longitudinallyextending edge of said bed and at an acute angle in intersectingrelationship thereto, heating said sheet to deformation temperature, andmoving it while so heated along said curved portion while said edge ofsaid sheet is held in said oriented position whereby said sheet deformsand is curved about an axis which is in intersecting relation to saidedge of said sheet, and cooling said sheet.

10. A method of curving a sheet of glass comprising: supporting saidsheet on gas above an elongated bed having a longitudinally extendingportion curved about an axis parallel to an edge of said bed, conveyingsaid sheet along said bed by contacting an edge of said sheet andorienting said edge of said sheet on a line intersecting relation tosaid edge of said bed, and heating said sheet to deformation temperatureas it is conveyed along said bed whereby said sheet conforms to thecurvature of said bed and is curved about an axis which is inintersecting relation to said edge of said sheet, and cooling saidsheet.

-11. Apparatus for conveying a sheet of glass comprising: a support bed,means supplying gas over said bed for supporting the sheet over saidbed, conveyor means disposed adjacent said bed and including a sheetsupport means extending over said bed to contact an edge of the sheetand to move the sheet along the bed, said support means having a surfacewith sufficient area disposed over said bed to permit said support meansto be supported at least in part by said gas.

References Cited UNITED STATES PATENTS 12/1965 Fredley et al. 651825/1966 Haley et a1 2141

